Colouring of sheathed continuous strands

ABSTRACT

A METHOD FOR THE SURFACE COLOURING OF AN ABSORBENT SHEATH ON A CONTINUOUS STRAND IN WHICH THE STRAND IS PASSED, WITH THE SHEATH BEING WET, LONGITUDINALLY THROUGH A ZONE OF ATOMIZED LIQUID DYE.

July 20, 1971 0. J. MOCK 3,594,223

COLOURING OF SHEAIHED CONTINUOUS STRANDS Filed Aug. 1, 1967 ZSheets-Sheet 2 United States Patent Office 3,594,228 Patented July 20, 1971 3,594,228 COLOURING OF SHEATHED CONTINUOUS TRANDS US. Cl. 117-231 Claims ABSTRACT OF THE DISCLOSURE A method for the surface colouring of an absorbent sheath on a continuous strand in which the strand is passed, with the sheath being wet, longitudinally through a zone of atomized liquid dye.

The present invention relates to the colour coding of cored strands and more particularly to the colouring of absorbent sheaths on continuous strands such as fibrous insulated wire or cable.

In a multistrand cable the individual wires are distinguished one from another each by a different colouring of its insulation. Pulp insulation is widely used on wires and cables and such insulation can be colour coded by dye or stain. Different types of fibrous pulps may be used such as manilla, wood, rag, cotton, jute, hemp or asbestos. The wire is coated with pulp insulation by passing it through a vat of pulp whereby the strand is embedded in a covering of the pulp after which it is polished and oven dried. In the past, dye was added to the liquid pulp mixture in the vat to colour code each strand but when it was desired to change the colouring code the unused dyed pulp had to be drained from the vat and stored or thrown away and the vat had to be cleaned in readiness for a new batch of pulp. This was a very expensive and time-consuming procedure.

In an improvement over the above method oscillating jets were devised to apply liquid dye in bands on the uncoloured pulp insulation of the strands. This type of strand marking apparatus is described in US. Pat. No. 2,428,284 to Western Electric Company, Incorporated, assignee of C. J. Krogel, issued Sept. 30, 1947. However, that development has been found to be disadvantageous in that the nozzles of the jets frequently become plugged which results in a considerable length of the continuously moving strand being left uncoloured and having to be scrapped. Other disadvantages of the oscillating jet are that: (1) because the dyeing of the strand takes place prior to the passage of the strand into the drying oven, the insulation is still relatively soft and frequently suffers physical damage from the force of the jet of colouring liquid; (2) as a result of the presence of dye within the pulp the insulation in its dry state is mechanically weakened; and (3) the oscillating apparatus is expensive to construct and maintain.

It is an object of the present invention to provide a method for colouring absorbent sheaths on continuous strands in which the penetration of the colouring into the sheath is controlled, by colouring the sheath when wet and employing a mist, to reduce the mechanical weakness imparted to the sheath by such penetration.

An example and embodiment of the invention is illustrated in the accompanying drawings in which:

FIG. 1 is a schematic flow diagram showing the steps of forming pulp insulation on a wire strand, including the step of colouring the wet insulation according to the present invention;

FIG. 2 is a cross sectional view in elevation of a spray chamber for earring out the invention;

FIG. 3 is an inlet end view of the spray chamber of FIG. 2 showing the right-hand side of the chamber in cross-section taken along the line 3-3 of FIG. 2 with the exhaust hood partially broken away;

FIG. 4 is a view in perspective of an atomizer and the associated fitting on the housing of the spray chamber to receive the atomizer; and

FIG. 5 is a view in cross section of the spray nozzle of the atomizer shown in FIG. 4.

In the schematic flow diagram of FIG. 1 a continuous strand of bare metal wire 10 as shown in cross-section A is unwound from a supply spool 11 into a pulp vat 12 where it passes around a cylinder mould 13 partially submerged in pulp liquid 14. Wire 10 emerges from vat 12 embedded in a strip coating 15 of pulp insulation ts shown in cross-section B. Coated wire 10 next passes through a polisher 16 between elements or shoes 17 axially rotated by a motor 18 which folds the lateral portions of strip coating 15 around the wire to form an annular sheath or layer of insulation 19 producing an insulated wire strand 20 as is shown in cross-section C. The wire 20 earring the wet insulation passes longitudinally through a spraying apparatus 21 in which insulation 19 is stained or coloured according to the present invention. Upon emergence from spraying apparatus 21 insulated wire strand 20 passes into a drying oven 22 where the moisture carried by insulation 19 from pulp vat 12 and spraying apparatus 21 is evaporated resulting in a dry strand which is wound on a take-up spool 23 for storage.

As shown in FIGS. 2 and 3 of the drawings, spray apparatus 21 consists of a housing 30 comprising an upper wall 31 contoured longitudinally (i.e. in the direction of travel of strand 20') to form two slopin portions 31a meeting at a crown 31b, a lower wall 32 also contoured longitudinally and a pair of fiat lateral end walls 33, all combining to form an enclosed chamber 34. Upper segments 33a of end walls 33 carry a pair of flanges 35 defining a groove into which the upper edge of lower segment 33b of each end wall 33 fits whereby the upper wall is removable from the lower wall. To facilitate this removal a pair of handles 36 are fixed to upper wall 31 at the rearward and forward ends thereof (in the direction of travel of strand 20). Upper and lower walls 31 and 32 are spaced one from another at both their rearward and forward ends an amount suificient to form a horizontal inlet slot 37 and a horizontal outlet slot 38 respectively. Horizontal edge 39 of upper wall 31 at inlet slot 37 and horizontal edge 40 of the upper wall at outlet slot 38 each slope gradually downward from a central point toward either end. Edge 39 of upper wall 31 is inturned while horizontal edge 41 of lower wall 32 at inlet slot 37 forms a lip underlying edge 39.

Horizontally disposed gutter strips 42 are fixed on the inner surface of upper wall 31 adjacent upper edges 39 and 40. Strips 42 slope downwardly from a central point toward each end adjacent but spaced from end walls 32a and slope laterally upward from wall 31.

An exhaust hood 43- is fixed to lower wall 32 of housing 31 and has a leading edge 43a forming, with edge 40 of upper wall 31, outlet slot 38. Exhaust hood 43 extends the full width of housing 31 and tapers downwardly to an outlet conduit 44 connected to a vacuum pump 45 which feeds into a reservoir 46 (see FIG. 1). The top opening of hood 43 carries a pair of inwardly projecting fixed baffles 47 sloping downwardly to form a centrally disposed slot 47a extending the width housing 31 between end walls 33b. Suitable filters (not shown) are provided to remove foreign matter from the liquid dye before it enters reservoir 46 by the action of pump 45. A plurality of circular apertures 48 are located in a lateral line parallel to crown 31b along that sloping portion 31a of upper wall 31 terminating in edge 39 of inlet slot 37. Mounted on wall 31 concentric with each aperture 48 is a locking ring 49 consisting. of a pair of apertured blocks 50 and 51 (see FIG. 4) defining therebetween a circular groove 52 laterally accessible by a pair of opposed recesses 53. In the embodiment shown in the drawings four apertures 48 and associated locking rings 49 are provided in upper wall 31.

Lower wall 32 of housing 30 is also contoured longitudinally with a shallow sloping portion 54 adjacent edge 41 of inlet slot 37 and a central well 55 formed by two steeply sloping portions 56 and a bottom portion 57 which is creased at 58 laterally between end wall segments 33b. Steeply sloping portion 56 of lower wall 32 adjacent shallow sloping portion 54 also carries a row of apertures 48 and locking rings 49. An aperture 59 is located in bottom wall 57 of well '55 and opens into a filter housing 60 fixed to lower wall 32. Filter housing 60 carries a plurality of stacked horizontal filters 61 which are removable from the filter housing for replacement as shown in broken lines in FIG. 3 of the drawings. A conduit 62 is connected to filter housing 60 through a lower opening 63 and feeds into reservoir 46.

As shown more particularly in FIGS. 4 and of the drawings, each aperture 48 and contiguous locking ring 49 is adapted to receive an atomizer 64 which is mounted on a disk plate 65 carrying a pair of opposed lugs 66 receivable in recesses 53 and groove 52. Each atomizer 64 consists of a junction member 67 to which a liquid line 68 leading from reservoir 46, an air line 69 fed by a pressure pump 69a and an outlet nozzle 70 are attached. Nozzle 70* consists of a body portion 71 having a central passage 72 connecting with liquid line 68 and a further passage 73 connected with air line 69. A spray head 74 is attached to nozzle 71 by a lock nut 75 and has a passage 76 suitably configured to provide a venturi which, when air is fed under pressure from line 69, draws liquid from line 68 through passage 72 which is mixed in passage 76 with the air to form a mist of atomized spray emanating from the spray head.

Each atomizer 64 when engaged in any one of locking rings 49 is directed towards a central region of chamber 34 in housing 30 running laterally between end walls 33. This central region is intersected by the path of strands moving through chamber 34 from inlet 37 to outlet 38, as shown in FIG. 2 of the drawings. Junction 67 carries a handle 79 for easier manipulation of each atomizer 64. To seal apertures 48 not having a spraying device 64, a plain disk plate 65 is provided carrying only handle 79.

In the operation of the example embodiment shown in the drawings a row of parallel insulated wire strands 20 is continuously passed longitudinally through inlet slot 37, chamber 34 and outlet slot 38 of housing 30. Any number of strands 20 may be accommodated by apparatus 21 governed only by the size of the particular apparatus. Liquid dye is directed into chamber 34 in atomized particles from atomizers 64, arrayed in apertures 48 preferably above the plane of strands 20 as shown in the drawings to form a mist in the chamber. Thus while the dye is directed towards the central region of chamber 34 it does not impinge in a jet or stream onto strands 20 but permeates the chamber. Here it should be pointed out that the term mist is used in this specification to mean a suspension of particles of a liquid in air (or other gas inert to the dye and to the strands being coloured).

Excess liquid dye collecting on the inner surfaces of housing 30 flows toward well 55 and outlet aperture 59 in lower wall 32 of the housing. The liquid dye collecting on the inner surface of upper wall 31 flows downwardly along sloping portions 31a into gutter strips 42 to drip from their ends adjacent end walls 33, thus clearing strands 20 and vgravitating to reservoir 46 by way of well 55. Foreign matter picked up by the liquid paint or dye within chamber 34 is removed from the liquid by filters 61 as the liquid passes to reservoir 46 for recirculation to atomizers 64.

Mist which would otherwise emanate from housing 30 through outlet slot 38 due to air currents created by strands 20 passing through the housing is inhibited from escaping from the housing by the operation of vacuum pump 45 which creates a reduced pressure in exhaust hood 43 and draws mist through lateral slot 47a between baflles 47. The baffles slop inwardly toward slot 47a so that any liquid dye collecting thereon flows toward the slot.

By the present invention, the outer surface of insulation 19 in each strand 20 is coloured but the liquid dye does not penetrate into the insulation to any appreciable extent. In this manner a minimum amount of dye is used and also the structural quality of the insulation is not impaired. Secondary control of dye penetration may be achieved by varying the pressure of the air supplied to atomizers 64 and hence varying the amount of liquid dye drawn from reservoir 46 and entrained in the air to increase or decrease the density of mist within housing 30. Such density of mist may also be achieved by varying the number of atomizers 64 and this is made possible by the provision of a double row of apertures 48 in housing 30, one row in upper wall 31 and one row in lower wall 32, which are sealed by disk plates 65 when not in use. Where density of mist is varied it may also be necessary to vary inversely the concentration of dye in the dye liquid to achieve a predetermined intensity of colour. Further control of dye penetration may of course be governed by the speed of travel of strands 20' through chamber 34 but such speed is governed primarily by the production of the strands and the employment of a mist reduces the need for a critical adjustment of strand speed in relation to concentration of dye.

It will be appreciated that the clogging of an atomizer 64 will not render the apparatus of the present invention inoperable since the mist within chamber 34 continues to be generated by the remaining atomizers and colouring is imparted to insulation 19 of strands 20 while the faulty unit is removed and cleaned. Thus there is no interruption in the flow of strands 20 through apparatus 21 and consequently no uncoated and unusable wires are produced.

Although the invention has been described with respect to a wire covered with pulp insulation it is applicable to any continuous cored strand having a fibrous insulation. Also, the mist of dye formed and maintained in chamber 34 could be generated by means other than the means shown.

I claim:

1. A method of colouring an absorbent sheath on a continuous strand, comprising the step of passing the strand, with the sheath being wet, longitudinally through a zone of atomized colouring liquid whereby only that portion of the sheath adjacent its surface is coloured.

2. A method as claimed in claim 1 in which the atomized colouring liquid is a mist of liquid dye, and including the step of varying the density of the mist whereby the intensity of colour of the sheath surface is preselectively altered.

3. A method as claimed in claim 2 in which the strand is a pulp insulated wire strand.

4. A method as claimed in claim 2 in which a plurality of said strands in parallel one with another are passed through the zone.

5. A method as claimed in claim 2 in which the mist is generated by a plurality of venturi atomizers.

6. A method as claimed in claim 5 in which the mist is directed into an enclosed chamber traversed by the strand.

7. A method as claimed in claim 2 in which the mist is maintained in an enclosed chamber traversed by the strand.

8. A method as claimed in claim 7 in which a zone of reduced pressure is provided within the chamber adjacent the strand emerging therefrom whereby mist is diverted and emergence thereof from the chamber is substantially prevented.

9. A method as claimed in claim 7 in which liquid dye collecting within the chamber in the lowest portion thereof is recirculated for re-use in forming said mist.

10. A method as claimed in claim 9 in which the recirculated dye is filtered.

References Cited UNITED STATES PATENTS 9/1947 Krogel 117-231UX 4/1961 Vatt et al. 1l8325X US. Cl. X.R. 

